1. Field of the Invention
The invention relates to devices and methods for controlling the flow rate of evacuation of contaminated gas from a surgical cavity during certain surgical procedures.
2. Description of the Related Art
During the performance of certain surgical procedures a surgeon may need to use a needle or a trocar device to deliver fluid into a body cavity, or a portion of a body, for the purposes of inflating or distending the body cavity to make it easier to see and perform the desired treatment. Common procedures in which insufflation is used include any type of an endoscopic surgical procedure, as well as laparoscopic or thoracoscopic surgical procedures performed in the abdominal or thoracic body cavities, respectively. In these procedures a blind incision, for example, or a Verres needle may be used to initially traverse the skin and tissue layers until the body cavity is entered for the purpose of passing a pressurized fluid, either a gas or a liquid, into the body cavity.
When a blind incision is made, a standard trocar assembly may then be passed through the incision and into the body cavity, whereupon the desired fluid is passed through the trocar into the body cavity. If a Verres needle has been used to penetrate the body cavity, an external gas source is attached to a proximal end of the needle projecting outwardly from the body cavity. Under pressure, the desired fluid flows through the needle and is delivered into the body cavity for inflating the body cavity. In either instance, this process is known as insufflation, in which the desired fluid, as well as any other substances, which may include drugs and anesthetics, is passed under pressure into the body cavity. A commonly used gas for this procedure is carbon dioxide. Depending on the patient's size, medical condition, the procedure to be performed, and the surgeon's preference, the gas is flowed into the body cavity at a rate of from 0.1 to 20 liters per minute.
As described, physicians may use trocar assemblies for the purposes of passing a pressurized fluid within a body cavity. Known trocar assemblies have a solid outer sheath or a sleeve that is sized and shaped to allow passage through the incision and tissue layers of a body so that the sleeve penetrates at least partially into the body cavity. This is accomplished by passing an elongate central retracting piercing element, referred to as a trocar or an obturator, through the sleeve and then passing the sleeve and the trocar together through the tissue. Once the sleeve is passed into the body cavity to the desired depth, the trocar is withdrawn from the sleeve.
During the insufflation process the pressurized fluid distends the body cavity to move the tissue layers outwardly of the body to create sufficient space in the cavity to observe and/or treat the organs and/or body structures therein. Once the body cavity is sufficiently distended and the obturator of the trocar is withdrawn from the lumen of the trocar sleeve, surgical instruments are typically passed through the lumen, while fluid continues to flow. This allows the surgeon to visualize the contents of the body cavity and proceed with the desired diagnostic and/or surgical procedures without damaging the remaining tissues, organs, or body structures within the body cavity.
Use of the surgical tools to cut body tissue generates contaminants and byproducts comprising smoke, aerosols, vapor and mist, etc., that disrupts the surgeons view of the surgical site and may present health risks to the surgical staff if exposed. Past attempts to safely and effectively remove the contaminated gas include simply releasing the smoke into the surgical environment, exposing the surgical team to the smoke and its contaminants. Other solutions comprise using the pressure in the surgical cavity to drive gas outflow, and filtration. This is unsatisfactory because reliance on the surgical cavity pressure may often be insufficiently effective in removing the contaminated gas as quickly as desired.
Other solutions use a vacuum source in line and in fluid communication with the surgical cavity. These solutions must be very controlled in restricting the fluid flow rate so as to permit a rapid gas/smoke removal while reinsufflating the surgical cavity to compensate for the gas/smoke that is removed in order to maintain sufficient pressure and distension within the surgical cavity. The abdominal cavity of the average patient comprises approximately two liters in volume, thus, a relatively low flow rate is required in order to remove smoke from the cavity. The smoke removal procedure may require a relatively rapid and full gas exchange within the surgical cavity in order to remove the smoke. Such gas/smoke removal should be done as quickly as possible in order to allow the surgeon vision of the site and to expedite the surgical procedure. A typical wall vacuum comprises relatively high flow rates, for example and without limitation between 40 to 100 liters per minute or more, which requires that flow restrictions be placed along the fluid conduit in order to bring the flow rate in the surgical cavity to within the range of between 0 to 30 liters per minute. Known solutions comprise providing a filter with sufficient resistance to reduce the flow rate of the fluid passing therethrough and/or predetermined orifice sizing combinations placed in fluid communication with the vacuum and surgical cavity. These solutions rely on manipulation of the filter composition and size and/or predetermined and fixed sized orifice combinations in order to achieve a safe flow rate.
Thus, all known devices provide predetermined flow rates; no known device or method provides infinitely variable selection of gas evacuation flow rates.
The present invention overcomes these deficiencies.